In a state where a stent is indwelled in a carotid artery region, when some plaques and thrombi flow into the peripheral side of the carotid artery, there is a possibility that the plaques and the thrombi are clogged into a cerebral blood vessel to cause cerebral infarction. In order to avoid the possibility, filters to be set in a blood vessel have been known heretofore as those capturing some plaques and thrombi without blocking the blood flow to the peripheral side relative to a stenosis portion of a blood vessel.
A filter described in Patent Literature 1 is provided with a distal end side slider and a proximal end side slider at the distal end and the proximal end, respectively, of the filter and the distal end side slider and the proximal end side slider are slidably inserted into and passed through a guide wire independently from each other. In the guide wire, a stopper is provided between the distal end side slider and the proximal end side slider. The stopper can abut on each of the distal end side slider and the proximal end side slider. Thus, the filter is movable to the proximal end side of the guide wire until the distal end side slider abuts on the stopper and is movable to the distal end side of the guide wire until the proximal end side slider abuts on the stopper.
The filter is inserted into a blood vessel through an introducer catheter. The filter housed in the introducer catheter is in a state where the distal end side slider and the proximal end side slider are separated from each other and the filter is contracted along the guide wire. Due to the fact that the filter is exposed from the introducer catheter, the distal end side slider and the proximal end side slider are brought close to each other, and then the filter which is elastically returned is expanded in the radial direction.
Patent Literature 2 discloses a filter device having a filter which has a bag shape having an opening portion formed at the distal end and having a closed proximal end and the filter which has a large number of small holes formed in the peripheral wall. In the filter, an opening portion holding wire is provided along the circumference of the opening portion and a marker coil is spirally wound around the opening portion holding wire. The opening portion holding wire has elasticity, and thus is deformable into a circular shape (ring shape) and a non-circular shape. The opening portion of the filter is deformed according to the deformation of the opening portion holding wire.
The filter is moved through the inside of a blood vessel in a state where the filter is housed in a sheath. In this case, the opening portion holding wire is contracted in a non-circular shape along the blood vessel in the sheath. When the sheath reaches a desired position in a blood vessel, the filter is drawn out of the sheath. Thus, the opening portion holding wire is expanded in a circular shape while being inclined with respect to the blood flow direction in the blood vessel, so that the opening portion of the filter is changed to the same shape. In the change, the position of the opening portion of the filter on an X-ray fluoroscopic screen is confirmed by the marker coil wounded around the opening portion holding wire.
A filter described in Patent Literature 3 has a conical shape, has an opening on the side of a proximal end portion, and has a tapered shape toward the side of a terminal end. The filter is fixed to a wire at each of the terminal end portion and the proximal end portion. The filter in an expanded state does not have a symmetrical shape with respect to the wire as the axis line.
A catheter described in Patent Literature 4 has two guide wire tubes for inserting a guide wire into each of branched blood vessels. Each tube has a marker at a predetermined position near the distal end. The marker is formed with a material which does not allow the transmission of X-rays. The shape of the marker is a ring shape or a ring shape having a notch. By X-ray imaging of the blood vessel into which the catheter is inserted, the marker can be visually recognized and the directions and the distal end positions of the two tubes can be grasped by the shape of the markers.